Catalytic Asymmetric Formal Insertion of Aryldiazoalkanes into the C–H Bond of Aldehydes: Synthesis of Enantioenriched Acyclic α-Tertiary Aryl Ketones
摘要:
A novel, catalytic enantioselective route to synthesize a variety of a-tertiary aryl ketones via a boron Lewis acid promoted formal insertion of aryldiazoalkane into the C-H bond of both aromatic and aliphatic aldehydes is described. In the presence of chiral (S)-oxazaborolidinium ion catalyst 1, the reaction proceeded in good yields (up to 94%) with excellent enantioselectivities (up to 99% ee).
Catalytic Asymmetric Cross-Couplings of Racemic α-Bromoketones with Arylzinc Reagents
作者:Pamela M. Lundin、Jorge Esquivias、Gregory C. Fu
DOI:10.1002/anie.200804888
日期:2009.1
Nickel box: The first catalytic asymmetric method for cross‐coupling arylzinc reagents with α‐bromoketones has been developed (see scheme). This stereoconvergent carbon–carbon bond‐forming process occurs under unusually mild conditions and without activators, thereby allowing the generation of potentially labile tertiary stereocenters.
Selective C–C bond establishment from plentiful carbonyl compounds, which represents a crucial route to get the value-added products, is still far from satisfying both academic and industrial needs. Here, confirmed by both experiment and theoretical calculation, we report versatile and efficient asymmetric cross-coupling between carbonyl radicals (from aldehydes) and aryl radicals (from aryl halides)